The role of macrophages in chronic suppurative otitis media associated sensory hearing loss

项目总结/摘要 我们请求NIH支持调查慢性化脓性中耳炎如何引起感觉性听力损失（SHL 中耳炎（CSOM）或严重的慢性中耳炎。CSOM，一种被忽视的热带疾病， 听力损失是造成儿童永久性听力损失的最常见原因。 发展中国家的团结合作它的特点是一个慢性排放感染中耳，目前没有 有效的药物治疗或治愈。铜绿假单胞菌（PA）是罪魁祸首。PA 通过鼓膜上的一个孔定殖中耳并将其自身建立成生物膜群落， 使治疗和完全根除感染的尝试复杂化。在疾病的过程中，感染会加重 并且随着生物膜内的细菌群体部分地对免疫攻击或局部免疫应答而减少。 抗生素这种细菌感染的消长通过一种新的途径导致永久性的感觉性听力损失。 未知机制我们的实验室最近创建并验证了一种新的PA CSOM动物模型， 人类的状况具体地说，我们在正确的状态（表型）下通过CD 3 PA创建感染， 剂量，导致感染持续超过六个月，蜡和减弱后，局部 氟喹诺酮治疗，并导致毛细胞死亡，随着时间的推移，像在人类疾病。先前 其他人的研究依赖于基于非PA细菌的急性感染模型。相比之下，我们独特的 PA CSOM模型现在允许我们观察内耳感染的发展并识别病原体 和/或可能导致感官听力损失的过程。我们的研究将有助于确定 CSOM中永久性听力损失是否可以预防，如果可以，指导治疗干预策略。 我们的目标包括：（1）确定耳蜗内发生结构变化的时间和性质 并评估这些变化发生时的巨噬细胞分布，（2）研究潜在的直接毛细胞 (HC)毒素和巨噬细胞诱导剂，通过CSOM外淋巴液取样，和（3）评估贡献 结合我们的CSOM小鼠模型， 用CD 68-GFP转基因报告小鼠，并分别用三重敲除小鼠品系， 巨噬细胞不能产生活性氧（ROS），同时还评估NLRP 3是否 炎性小体功能对于耳蜗中的HC损失是必需的。 总之，这些目标是一种全新的方法来治疗CSOM引起的感觉性听力损失。如果成功， 这些研究将支持未来对CSOM和铅的病理生理学机制的研究 PA的新治疗方法和预防CSOM中感觉性听力损失的潜在策略。

Project Summary / Abstract We request NIH support to investigate how sensory hearing loss (SHL) is caused by chronic suppurative otitis media (CSOM) or severe chronic middle ear infections. CSOM, a neglected tropical disease that afflicts 330 million people worldwide, is the most common cause of permanent hearing loss among children in the developing world. It is characterized by a chronically discharging infected middle ear, and there is currently no effective medical therapy or cure. The bacterium, Pseudomonas aeruginosa (PA), is the leading culprit. PA colonizes the middle ear via a hole in the tympanic membrane and establishes itself into a biofilm community, complicating attempts to treat and fully eradicate infection. Over the course of the disease, the infection waxes and wanes as the population of bacteria within the biofilm responds, in part, to immune attack or topical antibiotics. This waxing and waning of bacterial infection leads to permanent sensory hearing loss via an unknown mechanism. Our lab has recently created and validated a novel PA CSOM animal model that mimics the human condition. Specifically, we create the infection by inoculating PA in the right state (phenotype) and dose, which results in an infection that persists beyond six months, waxes and wanes upon topical fluoroquinolone therapy, and leads to hair cell death, over time, like in the human disease. Previous investigations by others relied on acute infection models based on non-PA bacteria. In contrast, our unique model of PA CSOM now allows us to observe development of the infection in the inner ear and identify agents and/or processes that may be causing the resulting sensory hearing loss. Our studies would help determine whether permanent hearing loss is preventable in CSOM and, if so, guide strategies for therapeutic intervention. Our Aims encompass: (1) determining the timing and nature of structural changes occurring within the cochlea and assessing the macrophage distribution as these changes occur, (2) investigating potential direct hair cell (HC) toxins and macrophage inducers through CSOM perilymph sampling, and (3) evaluating the contributions of resident and migrating macrophages towards hair cell loss in CSOM by combining our CSOM mouse model with the CD68-GFP transgenic reporter mouse and, separately, with a triple knockout mouse strain with macrophages unable to produce reactive oxygen species (ROS) while also evaluating whether NLRP3 inflammasome function is necessary for HC loss in the cochlea. Altogether these aims are a completely new approach to sensory hearing loss caused by CSOM. If successful, these studies will support future investigations into the mechanisms in the pathophysiology of CSOM and lead to novel treatments for PA and potential strategies to prevent sensory hearing loss in CSOM.